CVE-2026-107290Pydantic AI: Event loop blocked by quadratic title extraction in `web_fetch`
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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Pydantic AI is a Python agent framework for building applications and workflows with Generative AI. From 1.77.0 until 1.107.6 and 2.44.0, the local web_fetch_tool and the WebFetch local fallback process server-controlled responses with quadratic title extraction, whitespace normalization, and ordered-list numbering. An attacker-controlled page of modest size can therefore block the event loop for an extended period, stalling other agent runs and requests, while unsupported codecs or excessive HTML or JSON nesting can abort an individual run. This issue is fixed in versions 1.107.6 and 2.44.0.
- CVSS
- 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-1333
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Oct 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
pydantic pydantic-ai pydantic:ai (from the name) | from 1.77.0, < 1.107.6; from 2.0.0b1, < 2.44.0 | CNA record |
pydantic pydantic-ai-slim pydantic:ai_slim (from the name) | from 1.77.0, < 1.107.6; from 2.0.0b1, < 2.44.0 | CNA record |
pydantic pydantic_ai pydantic:pydantic_ai | from 1.77.0 before 1.107.6; from 2.0.0 before 2.44.0 | NVD |
References
- https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-fpf4-vwcp-v4hpx-refsource-confirm, vendor-advisory
- https://github.com/pydantic/pydantic-ai/pull/8397x-refsource-misc, patch, vendor-advisory
- https://github.com/pydantic/pydantic-ai/pull/8399x-refsource-misc, patch, vendor-advisory
- https://github.com/pydantic/pydantic-ai/pull/8418x-refsource-misc, patch, vendor-advisory
- https://github.com/pydantic/pydantic-ai/pull/84332x-refsource-misc, broken-link
- https://github.com/pydantic/pydantic-ai/pull/8434x-refsource-misc, patch, vendor-advisory
- https://github.com/pydantic/pydantic-ai/commit/2faa6181d8a17d83bc9516d035c5270db8730fa0x-refsource-misc, patch
- https://github.com/pydantic/pydantic-ai/commit/9cdc952e4c3319e85a3e04f2de49fbbb765bd38bx-refsource-misc, patch
- https://github.com/pydantic/pydantic-ai/commit/a93ea5226be1e93ae13131ae3f22287190411389x-refsource-misc, patch
- https://github.com/pydantic/pydantic-ai/commit/c3fd1cc1f15fdbf750d78e4e3ec1e8b4d6a3d920x-refsource-misc, exploit, patch
- https://github.com/pydantic/pydantic-ai/commit/fb92ccfc3ca2735dab877e2ed73856681bf72ad1x-refsource-misc, patch
- https://github.com/pydantic/pydantic-ai/releases/tag/v1.107.6x-refsource-misc, patch, release-notes, vendor-advisory
- https://github.com/pydantic/pydantic-ai/releases/tag/v2.44.0x-refsource-misc, patch, release-notes, vendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.